BRCA1 breast cancer risk up with pill use
TORONTO, Dec. 3 (UPI) -- Women who carry BRCA1 gene mutations, which already place them at high risk for breast cancer, are even more at risk if they used oral contraceptives before the age of 25, a study released Tuesday concludes.
The study data also indicate an increased breast cancer risk for women with the genetic mutation who used the pill for more than 5 years or used it before 1975. However, women with BRCA2 mutations did not show any increase risk from using the pill.
Researchers said they conducted the study because an earlier finding suggested birth control pills reduce ovarian cancer by about 60 percent among BRCA mutation carriers.
"We would like to be able to offer birth control pills to the BRCA carriers with the hope of preventing ovarian cancer without unduly affecting the risk of breast cancer," lead researcher Steven A. Narod of the University of Toronto, told United Press International. "That's why we did this study."
"I feel quite confident saying to my BRCA1 patients I recommend 5 years of oral contraceptive use after age 25," Narod said.
Because BRCA2 mutation patients showed no increased risk, oral contraceptives can be recommended for them without concern, he added.
Use of the pill by BRCA1 carriers before age 25 or for more than 5 years increased the chances of breast cancer by about 30 percent, the study found. Use of high-estrogen formulations of pills prior to 1975 increased the chances by 42 percent.
BRCA mutations in the general population occur in the range of about one woman in 500 to one in 1500, studies estimate. The 11-country study, which compared 1300 BRCA mutation carriers who had breast cancer with 1300 who did not develop the disease, will appear in the Dec. 4 issue of the Journal of the National Cancer Institute.
The lifetime risk of breast cancer for a BRCA1 or BRCA2 mutation carrier runs from 50 percent to 80 percent, studies show, though Narod believes it is closer to 80 percent than 50 percent.
This means, on average, if a BRCA1 mutation carrier has a 60 percent chance of developing breast cancer even without taking the pill before age 25 or taking it for more than 5 years, she would jump to about an 80 percent chance of developing breast cancer if she fell into either of those two categories, Narod said.
"This kind of information is helpful because young women who have family histories of breast cancer, and who have now had genetic testing within the family, are always looking for very specific advice," Patricia Ganz, director of cancer prevention and control at the Jonsson Cancer Center at the University of California, Los Angeles, told UPI.
"It is premature to recommend women with BRCA1 use oral contraceptives to prevent ovarian cancer," epidemiologist Janet Daling told UPI. Only a few studies support the claim, said Daling, with the Fred Hutchinson Cancer Research Center in Seattle. One study found oral contraceptives do not lower ovarian cancer in BRCA mutation carriers, she added.
First-time testing within a family for the presence of BRCA1 or BRCA2 mutations in the United States costs about $3,000. If testing already has been conducted on one family member, it simplifies the genetic search in her close relatives and drops the cost to about $350.